"We have the vaccines and the technical expertise to save millions of children's lives," said Anthony Lake, UNICEF executive director. "We must match our knowledge with our commitment to help the poorest, most vulnerable children."

Nearly two million children die every year from vaccine-preventable diseases. Currently one in five children is not vaccinated.

The GAVI Alliance, UNICEF and its partners aim to save an additional four million children's lives by 2015 by distributing several new life-saving vaccines, and prioritising children in the hardest to reach communities.

Many countries lack access to new vaccines. Pneumonia and diarrhoea cause one-third of all childhood deaths, and new vaccines against some causes of these deadly diseases now exist.

UNICEF is in the unique position of being involved at every stage of the immunization process, supplying vaccines to 56 per cent of the world's children and working on the ground in over 150 countries.